JPH02299903A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To reduce insufficient air supply due to the gasification of water content in a material itself by using polyester spinned yarn having a specified thickness in bleeder cords disposed on one surface or the like of a carcass member to prevent insufficient air supply in a tire. CONSTITUTION:In order to prevent defective accumulation of gas inside a tire, so-called insufficient air supply in the tire in the production process of the tire, bleeder cords are disposed at certain intervals on one or both surfaces of a carcass member and/or belt member in the tire. The air accumulation(gas) is transmitted through and absorbed by the bleeder cords to reduce the insufficient air supply in the tire. Then, in place of conventional cotton yarns, polyester spinned yarn having the thickness of 30-50S/1 is employed as the material of the bleeder cord. Thus, gas generated in the production process of the tire is efficiently transmitted and absorbed while a material having low hygroscopicity is utilized to reduce gasification and insufficient air supply due to water content.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to pneumatic tires, particularly carcass members,
This invention relates to improvements in bleeder cords arranged at regular intervals on one or both sides of a belt member.

[Prior Art] Traditionally, in the tire production process, a defect in which gas accumulates inside the tire (so-called air-injection defect) occurs, so a cotton yarn bleeder cord is attached at regular intervals to one or both sides of the carcass member or belt member. A method is used to place the This allows air pockets (gas bodies) included in the tire production process to be transmitted through and absorbed by the cotton yarn bleeder cord, thereby reducing air inadequacies in the tire.

[Problems to be solved by the invention] However, with the conventional cotton yarn bleeder cord, gas permeation,
Although the absorption performance is good, on the other hand, it has high hygroscopicity, so especially if moisture management is poor, the tire may contain a lot of moisture before being used for tire production, and the moisture will gasify during the tire vulcanization process and conversely enter the tire. There is a drawback that air inflow may occur.

An object of the present invention is to provide a pneumatic tire equipped with a bleeder cord that can reduce pneumatic defects that occur during the tire production process and improve production efficiency.

[Means for solving the problem] As a result of intensive study of the above problem, the above problem was solved by adopting polyester spun yarn with a thickness of 30 to 50 S/l instead of the conventional cotton yarn as the material for the bleeder cord. I discovered that there is a way to do this. In other words, this invention
This pneumatic tire is characterized in that a bleeder cord of polyester spun yarn having a thickness of 30 to 50 S is arranged on one or both sides of a carcass member and/or a belt member topped with rubber.

Bleeder cords are usually placed at regular intervals as in the past, but they may also be placed at unspecified intervals.
Moreover, it is preferable to arrange it over the entire width of the carcass member and/or the belt member.

[Function] Therefore, since the bleeder cord of polyester spun yarn is placed on the outer surface of the carcass member, etc., it permeates and absorbs the gas generated in the tire production process, similar to conventional cotton yarn, and reduces tire air inflow defects. In addition, since polyester spun yarn has lower hygroscopicity than cotton yarn, even if a bleeder cord using this is used, the conventional problem of gasification due to water content and air infiltration failure occurs during the tire production process. Since no points are generated, production efficiency is increased.

However, among polyester spun yarns, the thickness is 30~508/
It is especially preferable to use a polyester spun yarn with a thickness of 30 S/l or more. If a polyester spun yarn with a thickness of more than 30 S/l is used, separation due to the bleeder cord is likely to occur during running of the tire, resulting in a decrease in tire durability. On the other hand, if it is thinner than 50S/I, it will be difficult for air to pass through,
Air intake failure occurs.

[Example] Bleeder cords made of spun polyester yarn having a predetermined thickness shown in Table 1 are arranged at regular intervals of 5em on one side of the carcass part, and using this carcass member, the side on which the bleeder cords are arranged is connected to the crown part. A pneumatic tire with a tire size of 195/70R14 was prototyped by molding the tire so that it would be on the outside of the tire.

For comparison, we also made a prototype tire using cotton yarn as the material for the bleeder cord and using the same conditions.

In this example, the bleeder cords are arranged at regular intervals only on one side of the carcass member, but they can also be placed on both sides, and they can also be arranged together with the belt member or only on the belt member, but there are no particular limitations. It's not something you can do.

Table 1 shows the moisture content and air permeability of the bleeder cord disposed in the carcass member, and also shows the defective rate of tire air intrusion and tire durability during the manufacture of trial tires.

The moisture content (hygroscopicity) is measured by keeping the sample in an absolutely dry state and dividing it by the absolute dry weight relative to the increase in mass after leaving the sample in a standard state until moisture equilibrium is reached. The larger the number, the higher the moisture absorption.

To measure the air permeability, three sample cords are embedded in rubber and vulcanized to finish the sample, and then air pressure is increased to 40 degrees from one cord end using a compressor to prevent air from leaking from both cross sections on both sides of the sample. , 0 kg/Cn2
of dry air is sent in, and the amount of air permeation per 60 seconds is measured at the other end.

Tire durability was based on FMVSS109, and the same conditions were further extended to compare the running life (mileage), and index evaluation was performed using the tire according to Comparative Example 3 using a conventional cotton yarn bleeder cord as a control. The larger the number, the greater the durability.

From Table 1, compared to the conventional carcass member using cotton yarn bleeder cord (Comparative Example 3), the material of this example has a significantly reduced water absorption rate, excellent air permeability, and It is recognized that the air-intake defect rate is extremely low.

Furthermore, it is recognized that the bleeder cord made of polyester spun yarn with a thickness within a predetermined range is good in terms of defect/goods ratio and tire durability.

[Effects of the Invention] As described above, this invention differs from conventional cotton yarn bleeder cords in that the material of the bleeder cord is polyester spun yarn, and the polyester spun yarn has a certain thickness.
Since it is arranged in the belt member and carcass member, it has excellent gas permeability and low water absorption, so it can reduce air infiltration defects that occur during the tire production process, significantly increasing production efficiency. can be improved.

Furthermore, the present invention provides a pneumatic tire that reduces the occurrence of separation during running of the tire due to bleeder cords, and has improved tire durability.

Claims (1)

[Claims] (1) A pneumatic tire characterized in that a bleeder cord of polyester spun yarn having a thickness of 30 to 50 S/1 is arranged on one or both sides of a carcass member and/or a belt member.